A device which is the combination of an organic semiconductor transistor and an organic semiconductor light-emitting element is seen in Patent Reference 1. This device comprises a semiconductor layer formed of P3HT, a source electrode and a drain electrode disposed apart from each other on one surface of the semiconductor layer, a gate electrode disposed on the other surface of the semiconductor layer through an insulating film, a light emitting layer formed of MEH-PPV laminated on the drain electrode, and a negative electrode laminated on the light emitting layer. The drain electrode also works as positive electrode of the light-emitting element.
With this arrangement, current flows from the source electrode to the drain electrode through the semiconductor layer. Furthermore, supply of this current to the light emitting layer allows the observation of light emission from the light emitting layer. Patent Reference 1: Japanese Unexamined Patent Publication No. 2002-512451 (paragraph 0029, FIG. 2)